AjaxLine

Clean url's have big advantages. You can read in google about clean url's and url rewriting.

Example:
http://www.ajaxline.com/common-ajax
http://www.ajaxline.com/index.php?pid=12&something=24

Not hard to see that first url is self explained. Easy to memorize and more interesting for search bots.

In this post I'm not going to make Url rewriting overview. I just tell about my experience with 2 tools. I used them on Windows Server 2003 and IIS6.

ISAPI Filter

http://cheeso.members.winisp.net/IIRF.aspx
This tool allows to use syntax like in apache mod_rewrite. It's open source and free.
There is binaries and source http://www.codeplex.com/IIRF/Release/ProjectReleases.aspx?ReleaseId=5018
To install you just need to add isapi filter to your website in IIS6 and set rewrite rules in ini file. Works perfectly. Can be used not only in .NET

urlrewriter.net

Even more comfortable tool. Without isapi filters. All rules defined in web.config file. On site http://urlrewriter.net/ you can read instructions how to install it on different versions of windows.

Event for IIS6, which doesn't support ".*" mask for query processing you can find there solution.

Russian version of article